DIYARBAKIR, Turkey (Reuters) - Turkey is waging the largest operation in its history against Kurdish militants and the removal of civil servants linked to them is a key part of the fight, President Tayyip Erdogan said on Thursday, as more than 11,000 teachers were suspended.

The crackdown comes as Ankara also pushes ahead with a purge of tens of thousands of supporters of U.S.-based Muslim cleric Fethullah Gulen, accused by Turkey of orchestrating an attempted coup in July. Gulen denies any involvement.

Erdogan has repeatedly said he will not stop in his efforts to quash both the outlawed Kurdistan Worker's Party (PKK) or followers of Gulen, a network Ankara has labeled as FETO, meaning "Gulen Terror Organisation".

"We have run and are currently running the largest operations against the PKK terrorist organization in its history, both within and across our borders," Erdogan said.

"Whether it's the struggle against the PKK or against the FETO, an important dimension of this struggle is the removal of civil servants that are extensions of these organization within the state."

Turkey has sacked or suspended 100,000 people following the failed July 15 coup. At least 40,000 people have been detained on suspicion of links to Gulen's network and half of those arrested.

The scope of the crackdown has raised concern from rights groups and Turkey's Western allies who fear Erdogan is using the failed coup as pretext to curtail dissent.

Following the coup, there has been no let-up in the government's campaign against the PKK in the mainly Kurdish southeast. The group, seen as a terrorist organization by the United States, Turkey and the European Union, has waged a three-decade insurgency that has killed 40,000 people, most of them Kurds.

TEACHERS SUSPENDED

The government suspended 11,500 teachers over alleged links to the PKK, an official said on Thursday, after Prime Minister Binali Yildirim said during a visit to the region over the weekend that there were an estimated 14,000 teachers with links to the militants.

Security officials and local media reports said the state had appointed administrators to two municipalities in the southeastern province of Diyarbakir, although the local governor later denied it.

"Reports on the taking over of two mayor's offices in Diyarbakir do not reflect the truth. There has not been such an appointment at this stage. If there is an appointment, a statement will be made," the governor's office said in a statement.

Security officials, the private Dogan news agency, and the state-run Anadolu agency earlier said the government appointed the administrators to replace a pro-Kurdish party because of alleged support for Kurdish militants. Diyarbakir is a province in Turkey's largely Kurdish southeast.

The Democratic Regions Party (DBP), which runs the councils and many across the region, has been dubbed by Erdogan as an extension of the PKK, which has fought a three-decades-old conflict in the mainly Kurdish southeast.

The DBP is the local partner of Turkey's national pro-Kurdish opposition party, the Peoples' Democratic Party (HDP).